EPIX Pharmaceuticals Presents Findings from PRX-08066 Clinical Trials at National Institutes of Health Pulmonary Hypertension Meeting.

LEXINGTON, Mass. -- EPIX Pharmaceuticals, Inc. (NASDAQ: EPIX) announced today that data from three randomized, placebo-controlled Phase 1 clinical trials of PRX-08066, a novel serotonin 5-HT2B receptor antagonist, will be the focus of a poster presentation at the Evolution of Pulmonary Hypertension: Emerging Diseases and Novel Therapeutics meeting at the National Institutes of Health in Bethesda, Maryland on December 7-8, 2006. Data from these trials provide support for the ongoing Phase 2a clinical trial of PRX-08066 in patients with pulmonary hypertension (PH) associated with chronic obstructive pulmonary disease (COPD).

The presentation includes data from two Phase 1 clinical trials with PRX-08066 in healthy volunteers, along with results from a third study, a Phase 1b trial in athletes conditioned to exercise at high altitudes. The first Phase 1 trial was a single dose study and the second trial was a multiple dose, 14-day study; in both studies, subjects received either PRX-08066 or placebo. The Phase 1b trial assessed the effects of PRX-08066 on pulmonary artery pressure in athletes whose pulmonary pressures were increased by exposure to a reduced oxygen level (hypoxia). The results of this Phase 1b trial indicated that 200 mg of PRX-08066 given orally twice daily significantly reduced the increase in pulmonary artery blood pressure during hypoxic exercise, without affecting systemic blood pressure. PRX-08066 was well-tolerated in the single dose study up to 500 mg and up to 400 mg twice daily in the multiple dose study. The pharmacokinetic profile of PRX-08066 is consistent with once-daily dosing.

"There are currently no approved drugs to treat PH associated with COPD," said Michael G. Kauffman, M.D., Ph.D., chief executive officer of EPIX Pharmaceuticals. "There is a significant market opportunity for an effective treatment to selectively and safely reduce pulmonary artery blood pressure in these patients without affecting systemic blood pressure. We are very encouraged by these Phase 1 data and we look forward to the results from our ongoing Phase 2a clinical trial of PRX-08066."

EPIX initiated a Phase 2a clinical trial of PRX-08066 in August 2006 to evaluate the short-term efficacy and safety of PRX-08066 in patients with PH associated with COPD. The primary endpoint of the ongoing Phase 2a trial will assess the effect of PRX-08066 compared to placebo on systolic pulmonary artery pressure in patients with PH associated with COPD following two weeks of treatment. A subset of these patients will continue in an open-label extension for an additional six weeks. The trial also will assess the safety and tolerability of PRX-08066 during the course of therapy. Data from this trial are expected in mid-2007.

About PRX-08066

Discovered and designed using its PREDICT[TM] proprietary G-protein coupled receptor (GPCR) modeling and optimization technology, EPIX is developing PRX-08066 to provide both symptomatic improvement - through selective dilation of diseased pulmonary blood vessels - and to also slow disease progression - by inhibiting the thickening of the pulmonary artery vessels. EPIX believes PRX-08066 is the first 5-HT2B selective antagonist under development for pulmonary hypertension (PH) associated with chronic obstructive pulmonary disease (COPD). The 5-HT2B receptor represents a novel target for the treatment of pulmonary hypertension, as it has been linked to both pulmonary vasoconstriction, as well as the smooth muscle hypertrophy found in pulmonary vessels during pulmonary hypertension of various types.

EPIX also is exploring other potential indications in which the 5-HT2B receptor may play a key role.

About Pulmonary Hypertension

High blood pressure in the arteries that supply the lungs is called pulmonary hypertension. There are several types of pulmonary hypertension (PH). One of the many forms of PH is associated with chronic lung diseases such as chronic obstructive pulmonary disease (COPD). According to Datamonitor, PH is estimated to be present in approximately 15-20% of patients who have COPD, a progressive lung disease affecting nearly 30 million people worldwide which is characterized by airflow obstruction that interferes with normal breathing and impairs the ability to exercise and perform daily activities. There are currently no approved drugs for the treatment of PH associated with COPD.

About EPIX

EPIX Pharmaceuticals is a biopharmaceutical company focused on discovering, developing and commercializing novel pharmaceutical products through the use of proprietary technology to better diagnose, treat and manage patients. The company has a blood-pool imaging agent (Vasovist[TM]) approved and marketed in Europe and approved in Canada, Australia and Switzerland, and five internally-discovered therapeutic and imaging drug candidates currently in clinical trials targeting conditions such as depression, Alzheimer's disease, cardiovascular disease and obesity. These drug candidates include EP-2104R, a novel thrombus imaging agent which has completed a Phase 2a trial, PRX-08066 in Phase 2 clinical development for pulmonary hypertension associated with chronic obstructive pulmonary disease, and PRX-03140 which is in a Phase 2a clinical trial in Alzheimer's disease. EPIX also has collaborations with leading organizations, including Amgen, Cystic Fibrosis Foundation Therapeutics, and Schering AG (Germany). For more information about EPIX, please visit the company's website at www.epixpharma.com.

This news release contains express or implied forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, that are based on current expectations of management. These statements relate to, among other things, our expectations regarding the progress and results of our clinical development program for PRX-08066, the potential market opportunity for PRX-08066 and the timing of our presentation of the clinical trial data for PRX-08066. These statements are neither promises nor guarantees, but are subject to a variety of risks and uncertainties, many of which are beyond our control, and which could cause actual results to differ materially from those contemplated in these forward-looking statements. In particular, the risks and uncertainties include, among other things: risks that product candidates, including PRX-08066, may fail in the clinic or may not be successfully marketed or manufactured; risks relating to the our ability to advance the development of product candidates currently in the pipeline or in clinical trials, any failure to comply with regulations relating to our products and product candidates, including FDA requirements; failure to obtain the financial resources to complete development of product candidates; the risk that the FDA may interpret the results of our studies differently than we have; competing products may be more successful; our inability to interest potential partners in our technologies and products; our inability to achieve commercial success for our products and technologies; the possibility of delays in the research and development necessary to select drug development candidates; the risk that we may be unable to successfully secure regulatory approval of and market our drug candidates; and risks of new, changing and competitive technologies and regulations in the U.S. and internationally. Existing and prospective investors are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. We undertake no obligation to update or revise the information contained in this press release, whether as a result of new information, future events or circumstances or otherwise. For additional information regarding these and other risks that we face, see the disclosure contained in our filings with the Securities and Exchange Commission, including our most recent Quarterly Report on Form 10-Q.